The present invention generally relates to a storage system comprising a plurality of storage devices.
The storage systems using a HDD (hard disk drive) as a storage medium have been commonly used in an information system.
On the other hand, since the bit cost of flash memories has been decreasing in recent years, flash memories have become effective storage devices. The technology disclosed in U.S. Patent Application Publication No. 2007/0283079 describes the configuration in which a storage system has a plurality of flash memory device having a plurality of flash memories, and a controller having an I/O processing control unit for accessing a flash memory device specified by a designated access destination in an I/O request received from an external device from among the plurality of flash memory devices, and in which a parity group contains by the flash memory devices having the same internal configuration.